This invention relates to aluminum alloys and more particularly it relates to aluminum alloys suitable for high temperature applications such as pistons and other internal combustion engine applications.
In the use of aluminum for pistons, several alloys have been proposed. For example, J. E. Hanafee in a paper entitled "Effect of Nickel on Hot Hardness of Aluminum-Silicon Alloys", Modern Castings, Oct. 1963, proposes hypoeutectic and hypereutectic alloys. Under hypereutectic Hanafee suggests an alloy consisting of, in wt.%, 4.70 Ni, 10.2 Si, 1.12 Cu, 1.16 Mg, 0.53 Fe, 0.18 Ti, the balance aluminum. Hanafee suggests that the addition of Ni to a more complex alloy might be expected to improve room temperature and elevated temperature hardness by increasing the volume of stable hard particles. However, he noted that upon heating to 600.degree. F., the alloys underwent an initial rapid decrease in hardness and then, depending on the Ni content, maintained that hardness for up to 5 hours at temperature. In addition, Kersker et al (U.S. Pat. No. 4,681,736) disclose an aluminum alloy consisting essentially of about the following percentages of materials: Si=14 to 18, Fe=0.4 to 2, Cu=4 to 6, Mg=up to 1, Ni=4.5 to 10, P=0.001 to 0.1 (recovered), remainder grain refiner, Al and incidental impurities.